Steering columns in motor vehicles are known, with which a supporting unit, which can be connected with the chassis and is, for example, in the form of console parts, is provided, and an adjusting unit, which is held at the supporting unit and comprises, for example, an outer sleeve, is provided, a steering spindle being supported rotatably in the adjusting unit. With respect to the supporting unit, the adjusting unit is disposed displaceably, so as to, in the event of a crash, provide flexibility of the steering wheel by means of a corresponding displacement of the adjusting unit with respect to the supporting unit that is connected with the chassis, in order to improve crash behavior. When the adjusting unit is shifted with respect to the supporting unit, crash energy is absorbed over an energy absorption device, different designs being known here, by means of which crash energy can be absorbed in a controlled manner by way of the displacement path of the adjusting unit with respect to the supporting unit
For example, a steering column is known from the DE 10 2005 052 123 B3, for which an energy absorbing part, which has an elongated hole and is fixed to the adjusting unit, is provided between the supporting unit and the adjusting unit. A bolt, fixed to a rail and having enlargements, is guided in the elongated hole and, in normal operation, is fixed to the support unit by way of a locking unit at the supporting unit. In the case of a crash, the bolt can move in the elongated hole and, because of the enlargements of the bolt, the energy-absorbing part and, especially, the elongated hole of the energy-absorbing part can deform, so that a controlled energy absorption is attained by way of the displacement path.
An alternative concept is pursued in the DE 10 2008 034 807 B3, in which an adjusting unit is also disposed displayceably here with respect to the supporting unit; the adjusting unit and the supporting unit are not shifted mutually in normal operation; however, in the case of a crash, the adjusting unit shifts with respect to the supporting unit in order to absorb energy. Between an intervention part, which is locked to the supporting unit in normal operation, and a rail, which is fixed to the adjusting unit, a bending strip is provided, which is designed so that, in the event of a crash, a defined displacement of the adjusting unit with respect to the supporting unit absorbs energy due to deformation.
The previously described steering columns for motor vehicles are steering columns, which can be adjusted to fit the position of the steering wheel to the seated position of the driver, wherein at least a longitudinal alignment by shifting the adjusting unit with respect to the supporting unit can be carried out here. The position of the adjusting unit relative to the supporting unit, which is achieved after a corresponding adjusting process, is fixed by an appropriate locking mechanism so that, under normal operating conditions, the adjusted position of the adjusting unit with respect to the supporting unit is fixed. For this purpose, a tension mechanism, for example, is proposed, which acts over a tensioning bolt and at least one arresting element on the rail, which acts as a locking element, so that, in normal operation, the locking element is held immovably in the longitudinal direction of the steering column with respect to the adjusting unit. In the event of a crash, it can be shifted with respect to the adjusting unit with energy absorption, utilizing the energy absorption mechanism accomplished above by way of example.
For example, therefore, the deformation of the elongated hole of the energy-absorbing part or the deformation of the bending wire or bending strip can be specified by the energy-absorbing mechanism in accordance with a specified force-displacement behavior for the absorption of the crash energy over the displacement path for the crash case, since the relative displacement between the supporting unit and the adjusting unit may always be the same and is not changed by adjusting the length of the steering column.
For its development, the energy absorption mechanism described requires at least three parts in the form of an intervention part, a rail and the bolt or the bending strip.